Think over the problems and give your reasons for the right solution.
1. The streets of Novosibirsk are too narrow for heavy traffic. What can solve the problem of two-tiered roadways – bridges or tunnels? Mind the geological conditions and radon emissions.
2. New Zealand is an island country and it is a seismically active area. What is the best transport connection for such regions?
3. The territories beyond the Arctic Circle attract business attention because they are very rich in mineral recourses. Soon they will be populated and need some Railway and Motorway ES. What kinds are preferable for permafrost?
Make up some sentences using the following terminology.
1. Crash |
a) столкновение с препятствием |
2. Fairness |
b) обтекаемость |
3. Midstream |
c) фарватер |
4. Preliminary study |
d) предварительное исследование |
5. State surrounded by water |
e) островное государство |
6. Serviceable condition |
f) работоспособное состояние |
7. Technologically feasible |
g) технологически выполнимый |
Read this interview and make up your own dialogue with a partner “Bridge of the Future”: Europe-Africa Bridge. Use the words in the box.
Completion date, location of the bridge, structure, length of deck, width of deck, height of pylons above deck, height of deck above water, number of piers, number of cables, pylon building material, deck building material, total number of spans. |
Radio Tech presenter Tom Burns interviews engineer Galal Hamdy.
Tom: What project are you working on now?
Galal: We’re designing the world’s longest road bridge. Look at its small-scale model.
Tom: It’s really beautiful and looks very light. And what’s the bridge made of?
Galal: Yes, it looks light because it is light. It uses the minimum amount of material. But it is very strong.
Tom: Where will it be?
Galal: Between Morocco and Spain. It’ll connect Europe with Africa.
Tom: What are the specifications of the bridge?
Galal: Its total length will be almost 15 km long. In our design, the bridge will have two spans. Each span will be 4,800 m long.
Tom: That’s a very long span. How will that be possible?
Galal: The bridge will have three steel pylons on concrete piers. The pylons will be 1,000 m high. The deck will be very light and strong. It’ll be made of fiberglass.
Tom: How wide will the road deck be?
Galal: It’ll be 32 metres wide. It’ll have four lanes of traffic. The cables are in fact made of steel and the piers, of course, are made of reinforced concrete.
Tom: Many engineers think you won’t be able to build this bridge.
Galal: I don’t agree. I think we’ll complete it around 2030.
Unit 13
CONSTRUCTION OF SUPPORTS AND FOUNDATIONS
Read the text to have a clear idea of building materials and construction technologies for piers and foundations. Go down the word list and take note of professional terminology.
Bridges are designed, first, to carry their own permanent weight, or dead load; second, to carry traffic, or live loads; and, finally, to resist natural forces such as winds or earthquakes. All bridges need to be secure at the foundations and abutments. In most cases, bridge piers are made of concrete and reinforced concrete. Steel piers are used for flyovers and trestle bridges but not so frequently. The commonly used concrete pier may be subdivided into three groups according to construction technologies:
Monolithic or in situ concrete piers (fig. 13.1a). The concrete is poured against the falsework in situ. The falsework determines the pier shapes and dimensions.
Precast piers (fig. 13.1b). The piers are made of prefabricated concrete blocks.
Composite piers. They are used on a large scale and built from the precast concrete units and in situ concrete.
The methods of building foundations may be rather various and depend on geological conditions, ground strength, pier types and sizes, loads from the spans and piers. Where the soil is especially weak, wooden or steel piles are driven to support the foundations. After the concrete piers and abutments have hardened sufficiently, the erection of a concrete or steel superstructure begins.
Foundations are subdivided into two large groups: shallow foundations (fig. 13.1d) and deep foundations (fig. 13.1e,f, and g).
Shallow foundations are usually designed as monolithic ones on the natural bed. This technology is rather cheap and simple, but it is suitable for solid rock only (fig. 13.1d). The construction of shallow foundations begins with trench excavation. Rather deep trenches, excavated in a dry place for the flyover abutments or piers, viaducts or trestle bridges, demand a watertight enclosure or a sheet piling. The same is done if a trench is excavated in a river (fig. 13.1d) because the bed must be pumped dry to permit the pier construction. A sheet piling is made of metal bars driven to the calculated depth, into the ground, by a pile driver. Horizontal framing components are constructed of heavy timber, steel, or a combination of the two, hold the vertical piles in place. The structure must be able to resist the horizontal forces from the surrounding body of water when the inside water is pumped out of it. Then they place concrete against the casing, spread and compact it.
As a rule, the reinforcement is weak in tension but protects concrete from shrinkage cracks during its setting. The most difficult work is to pour the concrete for the foundations constructed in the river. Despite working water pumps, some water enters the trench, and the builders have to use additional grouting mortar (fig. 13.1d) to consolidate the soil in the water. Then they place the foundations.
Exercises:
Translate the following information into Russian, consulting the terminology list.
The primary function of a bridge is to carry traffic loads: heavy trucks, cars, and trains. Engineers must estimate the traffic load, and choose the appropriate bridge forms, which are able to resist the loads. Their choice will determine the type of construction method. Arches are normally fabricated in situ. After the construction of abutments (and piers, if the bridge is a multi span), an arch falsework is built. For a concrete arch, metal or wooden arch false work holds the poured concrete, and later is removed. For steel arches, a cantilevering method is standard. Each side of an arch is built out toward the other, supported by temporary cables above or by the arch falsework below until the ends meet. At this point, the arch becomes self-supporting, and the cables or arch falsework are removed.
When bridges requiring piers are built over a body of water, sinking caissons into the riverbed and filling them with concrete makes the foundations. Caissons are large boxes or cylinders that have been made from wood, metal, or concrete. In case of suspension bridges, towers are built atop the caissons.